The present invention relates to an EDM apparatus for effecting a cut by electrical discharges on an electrode workpiece by means of an electrode wire stretched and travelling between two guiding arms attached to the apparatus frame, the latter comprising a tank filled with a machining fluid and in which is mounted the electrode workpiece, means being provided for relatively displacing, in two directions, the tank and the two guiding arms, the tank being provided on at least one of its sidewalls with an opening through which one of the guide arms projects, and an arrangement preventing the machining fluid from leaking through the opening.
It is known to provide travelling wire EDM apparatus with a seal taking the form of a boot disposed between the tank wall and the electrode wire guiding arm projecting through an opening in the wall, for the purpose of preventing leakage of the machining fluid. Such boots are used in apparatus wherein the tank only recovers the machining fluid which is supplied to the machining zone. Boots are not practical in apparatus wherein the tank is filled with the machining fluid, in view of the fact that the boots are subjected to the pressure of the fluid filling the tank, which is applied against the tank walls.